In recent years, demand for thin-type energy storage devices such as electric vehicles, portable telephones, notebooks, and digital cameras is also rapidly increasing.
In such a thin-type energy storage device, a secondary battery is used, and a lithium secondary battery capable of achieving high energy density and high output driving is increasingly used as the secondary battery.
The lithium secondary battery is made of a pouch-type battery to achieve a thin-type structure, and it is advantageous that a large capacity battery can be obtained in a small area by connecting a plurality of pouch-type batteries.
Here, when a plurality of pouch-type batteries are connected, the capacity increases, but the heat generated when each battery is charged and discharged is concentrated in a small area, which makes it difficult to stably drive the batteries for a long time.
At present, it is necessary to develop a technology for extracting the heat of the pouch-type battery to the outside.
Korean Patent Application Publication No. 2009-0107443 (Patent Document 1) discloses a heat-radiating plate interposed between battery cells. The heat-radiating plate for a battery cell module, includes a composite sheet in which a matrix resin is filled with a thermally conductive filler, and carbon fibers which are inserted into the composite sheet wherein the carbon fibers are inserted to extend from an inside of the composite sheet to an edge of the heat-radiating plate.
When the heat-radiating plate of Patent Document 1 is inserted between battery cells to stack the battery cells, the thickness of the stacked module becomes thicker as the thickness of the heat-radiating plate is increased. Accordingly, since it is not possible to stack a large number of batteries in the same area, there is a disadvantage that the battery capacity is reduced.